In the past packaging or wrapping machines for cylindrical workpieces, such as rolls of bathroom tissue and paper towels, have suffered many drawbacks. For example, some packaging machines have not been able to package the bathroom tissues rolls or paper towel rolls as fast as these products are manufactured. This is especially true when only a small number of rolls are packaged together or when each roll is wrapped separately.
A holding area or accumulator is typically established between the paper winder that forms the rolls and the wrapping machine to hold the overflow of rolls or workpieces waiting to be wrapped. The accumulator is used for two primary reasons. First, if the wrapping machine malfunctions or must be shut down for repair, the winder can continue to wind paper rolls from the parent or material roll and does not have to be shut down. The wound rolls are stored in the accumulator until the wrapping machine is running again. Second, when it is necessary to install a new parent roll in the winder, the winder is typically run faster before it is shut down. This quickly fills the accumulator with wound rolls and the wrapping machine can continue to operate and wrap the paper rolls stored in the accumulator while the parent roll is changed. A parent roll change takes approximately 20 minutes. The goal is to change the parent roll, restart the winder and begin producing wound paper rolls again before the wrapper has wrapped all of the rolls in the accumulator. If the goal is achieved, the wrapping machine does not have to be shut down each time the parent roll is changed.
Additionally, many prior art wrapping machines utilize glue. For example, prior art single roll wrapping machines often require that glue be applied on either the wrapping paper or on the wound roll so that the leading edge of the wrapping paper can be adhered to the wound roll. The wound roll is then rotated to draw the wrapping paper around the outer periphery of the roll. Besides adding extra expense to the machine and the wrapped product, glue is typically messy and can easily clog in the wrapping machine.
Prior art wrapping machines also suffer from a not insubstantial amount of down time and a fairly high scrap rate. Scrap rate is commonly defined as the amount of product which is not suitably wrapped and therefore cannot be sold. Scrap must be either rewrapped or disposed of. While some prior art machines are capable of wrapping at substantially the same rate as our wrapping machine, they are less reliable. An unreliable machine can produce many scrap pieces before the wrapping machine can be stopped and the problem fixed. If the wrapping machine is down for a period of time greater than the time it takes for the winder to fill the accumulator, the winder must be shut down as well.
Additionally, even if the prior art machines are functioning normally and/or operating at a rate of production equal to our wrapping machine they will still have a scrap rate that is higher than the scrap rate of our invention.
In the industry, the reliability of a wrapping machine is typically judged by the number of rolls wrapped per day, excluding scrap. Our invention comprises a wrapping machine for wrapping rolls of bathroom tissue or paper towels that can wrap the product at a much faster rate when compared with prior art machines having the same reliability. Our machine is highly reliable and has a very low scrap rate. Unlike known high rate machines, our wrapping machines does not require any glue to perform the wrapping process.
A major difference between our wrapping machine and some prior art wrapping machines is that in our machine the wound paper roll is not rotated. Our wrapper utilizes a rotating carousel having a plurality of pockets. The wrapping paper and wound roll or workpiece are sequentially fed into each pocket as the carousel rotates and the wrapping process occurs as the carousel makes one complete revolution. A fully wrapped workpiece is ejected near the end of the revolution and another piece of wrapping paper and workpiece are inserted. The workpieces are not rotated, relative to the carousel, when wrapped; only the carousel is rotated.
It is an object of our invention to provide a wrapping machine that wraps cylindrical workpieces reliably at a high rate of speed with little or no scrap produced. It is an object of our invention to provide such a wrapping machine that utilizes clamping and underfolding devices to snugly wind and hold the wrapping paper against the workpiece while it is wrapped. It is a further object to provide such a wrapping machine that utilizes a pair of geneva wheel driven star wheels along the outer edges of each pocket and a pair of stuffer spindles to neatly and securely fold the wrapping paper over the outer parallel sides of the workpiece and tuck the wrapping paper into the workpiece center tube. It is another object of our invention to apply the wrapper around the workpiece in a neat and secure fashion such that the wrapper fits snugly about the workpiece and there are no gaps between the wrapper and the workpiece. It is yet another object of our invention to provide a wrapping machine that is compact, can be easily moved, and is flexible with respect to the location of its infeed and exit conveyors.
These and other objects of our invention will become apparent in the descriptions that follow. We know of no prior art that teaches or discloses our invention.